Removable wafer expander for die bonding equipment

ABSTRACT

A removable wafer expander for die bonding equipment for a singularized wafer supported by a flexible sticky substrate, the removable wafer expander provided with a first ring member to be coupled with a second ring member for remote expansion of the flexible sticky substrate therebetween before the mounting of the wafer expander onto the die bonding equipment.

BACKGROUND

1. Technical Field

The present disclosure pertains to a removable wafer expander for diebonding equipment.

2. Description of the Related Art

In the assembly of semiconductor devices, a wafer is mounted onto aflexible sticky foil held by a metal ring. After wafer sawing forsingularizing the dies within each wafer, every individual die has to bepicked from the sticky foil and placed directly on a substrate over adie attach material (package).

Thus is provided pick-and-place equipment with a die ejector system thatpushes the die back side to break the adhesion forces of the stickyfoil. A vacuum pick-up tool (robotic arm) picks the die and throughcoordinated motion places the picked die over the targeted placementposition.

Critical parameters for the pick-up process are the die back sideadhesion to the sticky foil and the separation between each die. Thelatter is mainly governed by the “wafer street width” and consequentlyby the cutting blade thickness.

The market trend is to continuously reduce the die size, maximizing thenumber of dies per wafer. Thus, stretching the sawn wafer to uniformlyenlarging the separation between each die is an option to be consideredto optimize the die pick-up process.

The deformation of the sticky foil happens on the die bonding equipment,and the expansion is not suddenly recovered on releasing the waferexpander from the die bonding equipment. In some cases a permanentdeformation occurs; therefore, it is not possible to use the waferanymore.

Thus, it is highly advisable that the wafer remains expanded by thewafer expander of the die bonding equipment until the full process iscompleted, namely until all the dies are removed from the sticky foil.

This is a limitation for multi-chip die bonding equipment. The bondingprocess is similar to the process described above, but after thecompletion of the first die the equipment has to change the waferbecause a different die is required for the same package.

Therefore, in such process where it is inherent to load and reload thesame wafer several times, the setup process is provided without waferexpansion.

As a consequence the lack of clearance between adjacent dies will inducevarious pick-up process issues.

BRIEF SUMMARY

The present disclosure provides a wafer expander for die bondingequipment by which it is possible to load and reload the same waferseveral times, maintaining the wafer in an expanded condition.

According to the disclosure, a removable wafer expander for a diebonding equipment for singularized wafer supported by a flexible stickysubstrate is provided, and it includes a first ring member to be coupledwith a second ring member for a remote expansion of the flexible stickysubstrate therebetween before the mounting of the wafer expander ontothe die bonding equipment.

It is in particular advisable to use the removable wafer expander onmulti-chip die bonding equipment. Several removable wafer expanders canbe prepared for the same equipment and mounted in turn thereon,maintaining several wafers contemporaneously expanded.

In accordance with another aspect of the present disclosure, a device isprovided that includes a first frame having a first holding member; asecond frame having a second holding member, the second frame sized andshaped so that the second holding member couples with the first holdingmember to engage and stretch the foil when the first frame and thesecond frame are coupled together.

In accordance with another embodiment of the present disclosure, anassembly is provided that includes a first frame; a second frame sizedand shaped to be coupled to the first frame; a flexible substrate havingone or more die releasably held thereto; and a first engaging memberassociated with the first frame and a second engaging member associatedwith the second frame, the first and second engaging members sized andshaped to be releasably mated together to securely hold the substrateand stretch the substrate such that additional space is provided on thesubstrate between each die mounted on the substrate. Ideally, the firstframe includes one of a channel or a protrusion and the other frameincludes the other of the channel and protrusion. Alternatively, thefirst frame can have one or more openings or channels and the secondframe can have one or more mating protrusions formed thereon that engageand stretch the substrate for creating additional space between the dieand otherwise holding the substrate taut to prevent unintentionalbending of the die as the die are removed from the substrate.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The characteristics and advantages of the present disclosure will appearevident from the following detailed description of an embodiment thereofillustrated as non-limiting example in the enclosed drawings, in which:

FIG. 1 is a top view of a first coupling ring of a removable waferexpander;

FIG. 2 is a sectional view according to line II-II of FIG. 1;

FIG. 3 is a top view of a second coupling ring of the removable waferexpander;

FIG. 4 is a sectional view according to line IV-IV of FIG. 1;

FIG. 5 is a longitudinal sectional view of the wafer expander in a restposition with the flexible sticky foil supporting the wafer before itsexpansion;

FIG. 6 is a longitudinal sectional view of the wafer expander in a workposition with the flexible sticky foil expanded;

FIG. 7 is a longitudinal sectional view of the wafer expander in a restposition after the sticky foil expansion.

DETAILED DESCRIPTION

Referring to FIGS. 1-4, a removable wafer expander 1 for a multi-chipdie bonding equipment is shown having a superior ring 2 and an inferiorring 3. The superior ring 2 is provided with an annular cavity 4 to becoupled with an annular protrusion 5 of the inferior ring 3.

Both rings 2-3 are provided with holes 11 for locking means, such asclips or fasteners, to maintain the rings in a work position (FIG. 6).Dies 6 of a singularized wafer 7 are mounted onto a flexible substrate,such as a sticky foil 8 supported by a metal ring 9 (wafer assembly 20).The equipment includes also a robotic arm 10 for the die pick-upprocess.

The multi-chip die bonding equipment is useful for packages to be loadedwith dies of different sizes. Away from the equipment, more than onewafer assembly 20 are expanded as follow.

A wafer assembly 20 is positioned between the superior and the inferiorrings 2-3 in the rest position of FIG. 5. The rings 2-3 clamp the waferassembly 20, expanding the sticky foil 8 (FIG. 6), due to the couplingbetween a protrusion 5 on the inferior ring 3 and the cavity 4 on thesuperior ring 2. The space between each die increases, thus the pick-upprocess made by the robotic arm 10 is easier. Therefore the criticalparameters of each wafer assembly 20 increase.

It is to be understood that the upright protrusion 5 can be formed on afirst frame, such as the superior ring 2 and sized and shaped to matewith a corresponding cavity or opening in a second frame, such as theinferior ring 3. Alternatively, the annular cavity can be one or moreopenings sized, shaped, and positioned on the first frame to mate withone or more protrusions on the second frame. The protrusion and channelare sized and shaped to hold the substrate or foil securely withouttearing of the same.

After the wafer expansion, the wafer expander is mounted on themulti-chip die bonding equipment for the pick-up process. If a controlunit calls for a different die supported by a different wafer expander,the previous wafer expander is unloaded from the equipment and a newwafer expander is loaded thereon.

When all the dies 6 are picked-up from its sticky foil 8, the rings 2-3release the permanently deformed die-empty sticky foil 8 (FIG. 7) for anew not deformed die-full sticky foil 8.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet, areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A removable wafer expander for die bonding equipment for asingularized wafer supported by flexible sticky means, comprising: afirst ring member coupled with a second ring member for remote expansionof the flexible sticky means therebetween before the mounting of thewafer expander onto the die bonding equipment.
 2. The removable waferexpander of claim 1, wherein the first ring member comprises an annularcavity coupled in a work position with an annular protrusion of thesecond ring member, the flexible sticky means included between the firstand second ring members, and expanded thereby.
 3. The removable waferexpander of claim 1, wherein the expander is adapted for use withmulti-chip die bonding equipment.
 4. The removable wafer expander ofclaim 1, wherein said ring members are held in work position by lockingmeans.
 5. The removable wafer expander of claim 1, wherein the stickymeans comprises sticky foil.
 6. A device for holding a flexiblesubstrate having objects mounted thereon, the device comprising: a firstframe having a first holding member; a second frame having a secondholding member, the second frame sized and shaped so that the secondholding member couples with the first holding member to engage andstretch the substrate when the first frame and the second frame arecoupled together.
 7. The device of claim 6, wherein the first holdingmember comprises one of either a channel and a protrusion, and thesecond holding member comprises the other of a channel and protrusion.8. The device of claim 7, wherein the substrate is stretched by thefirst and second holding members to increase space between the objectson the substrate.
 9. The device of claim 7, further comprising at leastone latch for releasably holding the first and second frames together.10. An assembly for holding objects, comprising: a first frame; a secondframe sized and shaped to be coupled to the first frame; a substratehaving one or more objects releasably held thereto; and a first engagingmember associated with the first frame and a second engaging memberassociated with the second frame, the first and second engaging memberssized and shaped to hold the substrate and stretch the substrate. 11.The assembly of claim 10, wherein the first engaging member comprisesone of a channel and a protrusion, and the second engaging membercomprises the other of the channel and the protrusion.
 12. The assemblyof claim 10, further comprising at least one latch for releasablyholding the first frame to the second frame with the first and secondengaging members in mating relationship and holding the foil in astretched condition.
 13. The assembly of claim 10, wherein the firstengaging member comprises a plurality of openings in the first frame andthe second engaging member comprises a plurality of extensions on thesecond frame member that are sized, shaped, and positioned to bereceived within the first engaging member openings.
 14. The assembly ofclaim 10, wherein the first engaging member and second engaging memberare structured to engage one another at one or more engagement pointsand hold the substrate at the one or more engagement points.
 15. Theassembly of claim 10, wherein the substrate comprises sticky foil.